Conventionally, as a sentence forming apparatus, a word processor 10 as shown in FIG. 23 is generally widespread. Such a word processor 10 has a keyboard 11 including a plurality of keys 11a which have such a size that people can easily operate by pressing them with their fingers, whereby input processing of sentences can be performed by using the keyboard 11. In FIG. 23, reference numerals 12 and 13 denote insert slots for floppy disks and a liquid crystal panel, respectively.
In recent years, a portable terminal apparatus such as an electronic organizer equipped with a sentence input function of the word processor as described above has been put to practical use. Representative examples of methods for performing input of sentences in such a portable terminal apparatus will be described below.
According to a first method, input of sentences is performed by using a keyboard which is much smaller than the keyboard 11 of the ordinary word processor 10 shown in FIG. 23 (e.g., which has a size of the palm of a hand).
According to a second method, a small keyboard is displayed on a display screen of the above-mentioned portable terminal apparatus, pressing of a displayed portion of a key on the display screen is detected by a pressure-sensitive sheet, and input processing of sentences is performed by using the displayed keyboard.
According to a third method, a handwriting detection portion utilizing a pressure-sensitive sheet is provided in the above-mentioned portable terminal apparatus, handwriting formed on the pressure-sensitive sheet is detected to recognize a pattern of characters, and input processing of sentences is performed by utilizing the recognition of such a character pattern.
However, the above-mentioned sentence input methods in the portable terminal apparatus have the following problems.
First, in the first method using a small keyboard, the keyboard is too small for people to manipulate the keys with their fingers, which makes it difficult to perform a key operation. Furthermore, it is required for those who are not familiar with a keyboard to look for a character on the top of each key for a key operation, and in inputting Japanese, after characters are input, they are required to be converted into appropriate kanji characters (i.e., Chinese characters), which results in a very bothersome input operation.
The second method in which a small keyboard is displayed on a display screen of a portable terminal apparatus also has the problems similar to those in the first method using a keyboard operation.
In the third method in which a pattern of input characters is recognized from handwriting by using a pressure-sensitive sheet, in the case where an unknown kanji character is input, it is required that the kanji character is once phonetically input by handwriting in the form of hiragana characters (i.e., Japanese phonetic characters), and the hiragana characters are converted into a kanji character. Thus, input of kanji characters is not necessarily performed efficiently by pattern recognition. Furthermore, in the case where there is a problem of a recognition ratio of handwritten characters (i.e., in the case where a recognition ratio is small), handwriting input is required to be frequently re-done. In order to enhance a recognition ratio, it is required to contrive a structure for performing pattern recognition of handwritten characters, leading to an increase in cost.
It is needless to say that the above-mentioned first to third methods can make it difficult for visually impaired people to perform input operation of characters.
Furthermore, to input characters by using a keyboard becomes very bothersome work for disabled people even in a tabletop information equipment equipped with an ordinary keyboard, as well as the above-mentioned portable terminal apparatus.
On the other hand, there is a game machine or the like in which characters can be input by using a pointing device such as a cross-pad, a trackball or a joystick, and a selection button. According to this method for inputting characters, hiragana characters are specified one by one, using the cross-pad and the selection button, for example, on a table in which all the hiragana characters are disposed in a predetermined arrangement, and a character name in a game, simple instruction sentences are input.
Accordingly, the method for inputting characters used in such a game machine is not intended for writing ordinary papers, E-mail, etc., and to write papers by using this method for inputting characters is very inefficient and impractical.